diff --git a/testable-core/src/main/java/com/alibaba/testable/core/compile/InMemoryJavaCompiler.java b/testable-core/src/main/java/com/alibaba/testable/core/compile/InMemoryJavaCompiler.java
index fa259b3..0569107 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/compile/InMemoryJavaCompiler.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/compile/InMemoryJavaCompiler.java
@@ -69,9 +69,7 @@ public class InMemoryJavaCompiler {
 			throw new CompilationException("No source code to compile");
 		}
 		Collection<SourceCode> compilationUnits = sourceCodes.values();
-		CompiledCode[] code;
-
-		code = new CompiledCode[compilationUnits.size()];
+		CompiledCode[] code = new CompiledCode[compilationUnits.size()];
 		Iterator<SourceCode> iter = compilationUnits.iterator();
 		for (int i = 0; i < code.length; i++) {
 			code[i] = new CompiledCode(iter.next().getClassName());
@@ -81,7 +79,7 @@ public class InMemoryJavaCompiler {
 		JavaCompiler.CompilationTask task = javac.getTask(null, fileManager, collector, options, null, compilationUnits);
 		boolean result = task.call();
 		if (!result || collector.getDiagnostics().size() > 0) {
-			StringBuffer exceptionMsg = new StringBuffer();
+			StringBuilder exceptionMsg = new StringBuilder();
 			exceptionMsg.append("Unable to compile the source");
 			boolean hasWarnings = false;
 			boolean hasErrors = false;
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/compile/README.md b/testable-core/src/main/java/com/alibaba/testable/core/compile/README.md
index a2f284d..907c795 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/compile/README.md
+++ b/testable-core/src/main/java/com/alibaba/testable/core/compile/README.md
@@ -1,4 +1,4 @@
-This part of code is under [Apache License Version 2.0](LICENSE), modified from [InMemoryJavaCompiler](https://github.com/trung/InMemoryJavaCompiler) with several PRs merged and other refactorings (e.g. dropping unnecessary dependence and avoid throwing raw Exception).
+This part of code is under [Apache License Version 2.0](LICENSE), modified from [InMemoryJavaCompiler](https://github.com/trung/InMemoryJavaCompiler) with modification (e.g. dropping unnecessary dependence and avoid throwing raw Exception).
 
 Many thanks to the origin author and contributors of this lovely library:
 - [trung](https://github.com/trung)
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/compile/SourceCode.java b/testable-core/src/main/java/com/alibaba/testable/core/compile/SourceCode.java
index e882e15..7688e3f 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/compile/SourceCode.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/compile/SourceCode.java
@@ -1,17 +1,16 @@
 package com.alibaba.testable.core.compile;
 
 import javax.tools.SimpleJavaFileObject;
-import java.io.IOException;
 import java.net.URI;
 
 /**
  * Created by trung on 5/3/15.
  */
 public class SourceCode extends SimpleJavaFileObject {
-	private String contents = null;
-	private String className;
+	private final String contents;
+	private final String className;
 
-	public SourceCode(String className, String contents) throws Exception {
+	public SourceCode(String className, String contents) {
 		super(URI.create("string:///" + className.replace('.', '/')
 				+ Kind.SOURCE.extension), Kind.SOURCE);
 		this.contents = contents;
@@ -22,8 +21,8 @@ public class SourceCode extends SimpleJavaFileObject {
 		return className;
 	}
 
-	public CharSequence getCharContent(boolean ignoreEncodingErrors)
-			throws IOException {
+	@Override
+	public CharSequence getCharContent(boolean ignoreEncodingErrors) {
 		return contents;
 	}
 }
diff --git a/testable-core/src/main/java/com/alibaba/testable/core/util/ConstructionUtil.java b/testable-core/src/main/java/com/alibaba/testable/core/util/ConstructionUtil.java
index 78d3aa3..3d98b4d 100644
--- a/testable-core/src/main/java/com/alibaba/testable/core/util/ConstructionUtil.java
+++ b/testable-core/src/main/java/com/alibaba/testable/core/util/ConstructionUtil.java
@@ -4,25 +4,30 @@ import com.alibaba.testable.core.compile.InMemoryJavaCompiler;
 
 import java.lang.reflect.Method;
 
+import static com.alibaba.testable.core.constant.ConstPool.DOLLAR;
+import static com.alibaba.testable.core.constant.ConstPool.DOT;
+
 public class ConstructionUtil {
 
     private static final String TESTABLE_IMPL = "$TestableImpl";
-    private static final String TESTABLE_OMNI_PKG = "com.alibaba.testable.omni";
 
     public static <T> T generateSubClassOf(Class<T> clazz) throws InstantiationException {
         StringBuilder sourceCode = new StringBuilder();
-        sourceCode.append("package ").append(TESTABLE_OMNI_PKG).append(";\n")
+        sourceCode.append("package ").append(clazz.getPackage().getName()).append(";\n")
                 .append("public class ").append(getSubclassName(clazz))
-                .append(clazz.isInterface() ? " implements " : " extends ").append(clazz.getName()).append(" {\n");
+                .append(clazz.isInterface() ? " implements " : " extends ")
+                .append(clazz.getName().replace(DOLLAR, DOT))
+                .append(" {\n");
         for (Method m : clazz.getMethods()) {
 
         }
         sourceCode.append("}");
 
         try {
-            Class<?> helloClass = InMemoryJavaCompiler.newInstance()
-                    .compile(TESTABLE_OMNI_PKG + "." + getSubclassName(clazz), sourceCode.toString());
-            return (T) helloClass.newInstance();
+            return (T) InMemoryJavaCompiler.newInstance()
+                    .useParentClassLoader(clazz.getClassLoader())
+                    .compile(clazz.getPackage().getName() + DOT + getSubclassName(clazz), sourceCode.toString())
+                    .newInstance();
         } catch (Exception e) {
             throw new InstantiationException(e.toString());
         }